1. Field of the Invention
The present invention relates to a titanium-mica composite material. More specifically, it relates to a titanium-mica composite material suitable for use as a colorant or pigment providing a colored pearl gloss in, for example, coating compositions, cosmetics, plastics, printing inks, paints, ornaments, daily necessities, fiber goods, and ceramics, and further suitable for use as a conductive material and electromagnetic wave shield in, for example, conductive layers and recording layers in recording papers and antistatic materials. The titanium-mica composite material according to the present invention exhibits an excellent color tone (e.g., chroma and brightness), and an excellent safety, light resistance, chemical resistance, solvent resistance, and heat resistance.
2. Description of the Prior Art
As is well known in the art, conventional titanated mica composite materials used, as a pigment, in, for example, cosmetics, paints, and plastics, comprise mica and a titanium dioxide layer formed coated on the surface of the mica, because these conventional titanated mica composite materials have a pearl gloss and various interference colors. These titanated mica pigments are generally prepared as disclosed in Japanese Examined Patent Publication (Kokoku) No. 43-25644 by hydrolyzing an aqueous solution of the inorganic acid salt of titanium (e.g., titanyl sulfate) in the presence of mica to deposit hydrous titanium oxide on the surface of mica, followed by heating, although these titanated mica pigments also can be prepared by a vacuum deposition method. As the starting mica, muscovite is generally used, but biotite or other mica can be also used. The mica is previously subjected to aqueous grinding and sifting to obtain powder particles having a uniform particle size. The resultant titanated mica pigments exhibit various interference colors, depending upon the thickness of the titanium dioxide layer coated on the surface of the mica. The interference colors are generally silver when the titanium dioxide content is 10% to 26% by weight, gold when the titanium dioxide content is 26% to 40% by weight, red, blue, and green when the titanium dioxide content is increased from 40% by weight to 50% by weight, and higher order interference colors when the titanium dioxide content is 50% to 60% by weight.
The conventional titanated mica pigments thus prepared have a pearl gloss and various interference colors. However, the appearance colors thereof are always near or close to white and pigments having a bright appearing color in agreement with the interference color cannot be obtained.
Various kinds of color pigments such as iron oxides, ferric ferrocyanide, chromium oxides, carbon black, and carmine have been heretofore incorporated into the above-mentioned titanated pigments to obtain various colored appearance. However, the stabilities of, for example, the safety, light resistance, chemical resistance, solvent resistance, and heat resistance of these colored titanated mica pigments largely depend upon the properties of the color pigments incorporated thereinto. For example, blue titanated mica pigments mainly containing ferric ferrocyanide result in undesirable color fading in an alkaline solution and are degraded and faded at a temperature of 200.degree. C. to 300.degree. C. In addition, although green titanated mica pigments comprise a mixture of iron oxide and ferric ferrocyanide or chromium oxides, these pigments have a poor, for example, chemical resistance and heat stability, and have possible disadvantages from the safety point of view due to the toxicity of the chromium. Thus, the application ranges of these pigments are limited. Furthermore, blue or green organic pigments such as phthalocyanine blue, brilliant blue FCF aluminum lake, Quinizarin green, and phthalocyanine green have a poor safety and, for example, heat resistance, light resistance, and chemical resistance, and therefore, these organic pigments are not substantially used for coloring pearl gloss materials. On the other hand, red titanated mica composite pigments containing carmine are color faded due to light. Furthermore, the colored titanated mica pigments containing the color pigments cause color segregation or foreign odor generation in a solvent or various compositions (e.g., cosmetics) when color pigments are incorporated.